CAIRO — Iran's leadership faced sharp criticism Wednesday from top clerics and even conservative supporters over prison abuses, including detainee deaths and the brutal beatings of protesters arrested in the post-election crackdown.

In a move likely to anger the opposition, officials announced the first trials will begin Saturday, with the prosecution of around 20 protesters. They include some accused of sending images of the unrest to the media.

Top pro-reform politicians will be tried later for allegedly ordering riots, officials said. The opposition has said detainees were tortured to extract false confessions for the courts.

The bodies of several young protesters have been turned over to their families in recent weeks, all showing signs of beatings or other abuse while in custody, according to pro-opposition Web sites, citing accounts from relatives. Among them was the son of a prominent conservative, which has brought a wave of criticism from the camp that generally backs the government.

Opposition leader Mir Hossein Mousavi and his allies were planning a ceremony Thursday in the sprawling Behesht-e Zahra cemetery outside Tehran to honor those who died in the fierce suppression of the protests. Supporters also plan rallies in various parts of the capital – raising the likelihood of new clashes with security forces.

Putting further pressure on Iran's leadership, several top theologians harshly condemned the crackdown – a significant show of anger from the Islamic republic's spiritual patrons.

One of them, outspoken dissident Ayatollah Hossein Ali Montazeri, derided an order by the supreme leader this week to close Kahrizak prison, where at least one detainee was killed. "Can the government deceive people by closing a detention center and blaming all the faults on a building?" he said in a statement Wednesday.

"What benefit does the government gain from the crisis, except angering the majority of the people and weakening the Islamic republic?" he asked, demanding the prosecution of those responsible for abuses.

Another senior cleric, Ayatollah Asadollah Bayat Zanjani, said: "We are witnessing sorrowful acts committed in the name of the regime and under the banner of God that bring pain to the heart of all supporters of the Islamic republic."

Montazeri, Zanjani and two other clerics who have spoken out against arrests this week are among the "marajeh-e taqlid," or "objects of emulation," the highest theological rank in Shia Islam. They do not hold political positions but have powerful spiritual authority.

In the days after the June 12 presidential election, hundreds were arrested when police, the elite Revolutionary Guards and the Basij militia clamped down on the massive protests that erupted in support of Mousavi's claim of fraud in the vote. Since then, the wave of arrests have continued – especially during the sporadic, smaller protests that have broken out in recent weeks.

Many are being held in secret locations, and families often spend weeks trying to find out who is holding their loved ones. Accounts from released prisoners appeared on opposition Web sites this week, describing beatings and other abuse at the hands of guards and interrogators.

One told of being held at Kahrizak prison on Tehran's southern outskirts since his arrest in a July 9 protest.

"We were at least 200 people in one room, and everyone was getting beatings with sticks. The groans filled the place ... The walls were all bloody," he wrote. At one point the guards turned out the lights and beat the prisoners for a half hour in complete darkness, said the protester, who said he was released on Monday. He listed the names of six prisoners he believed died during the assaults.

As in other prisoner statements, he wrote anonymously because he had been warned not to speak of his detention. His and the other accounts could not be independently confirmed.

Another released prisoner said he was taken to a police station and beaten, and then police lay him and others in a bathroom, their legs tied up behind their backs, and forced them to lick a toilet.

In one of the most recent prison deaths, the family of 24-year-old Amir Javadi Langroudi was told last weekend to come to a Tehran hospital to pick up the body of their son, also arrested during the July 9 demonstrations, Langroudi's father said in a letter posted on opposition Web sites. The body showed signs of abuse and torture, the Web sites reported.

Authorities have not addressed specific claims of abuse. On Wednesday, police chief Gen. Ismail Ahmadi Moghaddam acknowledged one death in custody, but suggested it was due to a meningitis outbreak. He indirectly admitted some wrongdoing by police, saying, "If we do not observe the law, some in the public will ignore the law, too."

"In cases where damages were caused by the police, I have ordered officials to give compensation," he said.

The number of those killed since the election remains unclear. On Wednesday, an official with a parliament commission investigating detainees' conditions put the number at 30 – up from the 20 dead police announced weeks ago. Human rights groups say the number is likely several times that amount.

The clerical leadership has taken some steps to try to defuse the anger. On Tuesday, 140 detainees were released from Tehran's Evin prison, and authorities are promising to free more. A day earlier, Supreme leader Ayatollah Ali Khamenei ordered the closure of Kahrizak.

But even conservative politicians said that was not enough. Two influential lawmakers, Ali Mottahari and Ahmad Tavakkoli, said those responsible for deaths and abuse should be prosecuted.

The upcoming trials are likely to further anger opposition supporters. The state news agency IRNA said the "around 20" defendants whose trials begin Saturday have been indicted on charges ranging from carrying weapons and attacking police to "sending images of the unrest to the media of the enemy."

IRNA said that the defendants included some who had contact with the Mujahedeen-e Khalq – a dissident group of Iranian exiles – and members of the Bahai faith, which has been banned in Iran since the 1979 Islamic revolution and whose followers are often targeted by the government.

It said a later phase of trial would include those "who ordered the post-election unrest," a reference to opposition politicians.

The parliament commission official, Farhad Tojari, suggested two of the foremost jailed pro-reform politicians, Mostafa Tajzadeh and Behzad Nabavi, would face trial. "Their crimes are of a security nature and very significant," he told the ILNA news agency.